Shamoo, MacLennan and their coworkers have studied the trypsin digestion of the ATPase from the sarcoplasmic reticulum (SR) membrane. They have tentatively correlated three fragments with the ATPase activity of the ATPase, with an activity that they describe as a 'gate' that confers ionic specificity to the SR membrane, and with an activity that they describe as nonspecific ion pore. The last of these fragments is apparently membrane-sequestered in the original SR membrane and is supposed to retain its pore function even if denatured, isolated, and then reincorporated into lipid bilayers. Our overall objectives are to isolate this nonspecific ion pore, verify its function, and then characterize this pore both chemically and structurally. The chemical analysis will include amino acid analysis and SDS-gel size characterization of the polypeptide fragments making up the pore. The structural analysis will rely on circular dichroism and Raman spectroscopy.